The DNA Core will provide the necessary reagents, such as oligonucleotides, for the various phases of the experiments in this program project. It will assist investigators in designing and synthesizing PCR primers and oligo probes for vector construction and offer custom service for conjugation of oligonucleotides to biotin, fluorescein and other reagents when needed. These oligonucleotides will be synthesized in the HHMI core facilities and recharged to the investigators at a cost approximately 1/3 of that from commercial laboratories. The Core will also provide for DNA sequencing and the sequences will be provided on a computer floppy disk, which can be read by DNA software. The second component of this Core is to provide vectors which promote the efficient transfer and regulated expression of beta-globin genes. A high titer beta- and gamma-globin construct under the control of the LCR will be available to researchers in this program project. In addition, newer vectors expressing gamma-globin genes at high levels will also be available to investigators in this program project. The viruses designed by other investigators' projects will also be packaged in novel packaging cell lines in order to infect hematopoietic stem cells. Advice to investigators in various aspects of vector work will be offered, specifically in Projects l, 2, 4, and 5.